One of the number one reasons I use Ettore squeegees and not some of the newer products is I believe their rubber is #1. Thousands of window cleaners agree. Haha
Using someone else's rubber in any manufacturer's squeegee design may not work out so well because the rubbers are all made slightly different. PolznBladz made a video showing the differences and the incabatability of the rubbers with different channels. It was great he had about four different makes and showed how the rubbers were wrong. Of course the video was taken down.